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Epitestosterone
Epitestosterone, or isotestosterone, also known as 17α-testosterone or as androst-4-en-17α-ol-3-one, is an endogenous steroid and an epimer of the androgen sex hormone testosterone. It is a weak competitive antagonist of the androgen receptor (AR) and a potent 5α-reductase inhibitor. Structurally, epitestosterone differs from testosterone only in the configuration at the hydroxy-bearing carbon, C17. Epitestosterone is believed to form in a similar way to testosterone; a 1993 study found that around 50% of epitestosterone production in human males can be ascribed to the testis, although the exact pathway of its formation is still the subject of research. It has been shown to accumulate in mammary cyst fluid and in the prostate. Epitestosterone levels are typically highest in young males; however, by adulthood, most healthy males exhibit a testosterone to epitestosterone ratio (T/E ratio) of about 1:1. Society and culture Detection of athletic doping It has been shown that exog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doping (Sport)
In competitive sports, doping is the use of banned athletic performance-enhancing drugs by athletic competitors as a way of cheating in sports. The term ''doping'' is widely used by organizations that regulate sporting competitions. The use of drugs to enhance performance is considered unethical, and therefore prohibited, by most international sports organizations, including the International Olympic Committee. Furthermore, athletes (or athletic programs) taking explicit measures to evade detection exacerbate the ethical violation with overt deception and cheating. The origins of doping in sports go back to the very creation of sport itself. From ancient usage of substances in chariot racing to more recent controversies in doping in baseball, doping in tennis, doping at the Olympic Games, and doping at the Tour de France, popular views among athletes have varied widely from country to country over the years. The general trend among authorities and sporting organizations over the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1980 Summer Olympics
The 1980 Summer Olympics (russian: Летние Олимпийские игры 1980, Letniye Olimpiyskiye igry 1980), officially known as the Games of the XXII Olympiad (russian: Игры XXII Олимпиады, Igry XXII Olimpiady) and commonly known as Moscow 1980 (russian: link=no, Москва 1980), were an international multi-sport event held from 19 July to 3 August 1980 in Moscow, Soviet Union, in present-day Russia. The games were the first to be staged in an Eastern Bloc country, as well as the first Olympic Games and only Summer Olympics to be held in a Slavic language-speaking country. They were also the only Summer Olympic Games to be held in a self-proclaimed communist country until the 2008 Summer Olympics held in China. These were the final Olympic Games under the IOC Presidency of Michael Morris, 3rd Baron Killanin before he was succeeded by Juan Antonio Samaranch, a Spaniard, shortly afterwards. Eighty nations were represented at the Moscow Games, the smal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5α-Reductase Inhibitors
5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes of 5α-reductase encoded by the genes SRD5A1, SRD5A2, and SRD5A3. 5α-Reductases catalyze the following generalized chemical reaction: :a 3-oxo-5α-steroid + acceptor a 3-oxo-Δ4-steroid + reduced acceptor Where a 3-oxo-5α-steroid and acceptor are substrates, and a corresponding 3-oxo-Δ4-steroid and the reduced acceptor are products. An instance of this generalized reaction that 5α-reductase type 2 catalyzes is: :dihydrotestosterone + NADP+ \rightleftharpoons testosterone + NADPH + H+ where dihydrotestosterone is the 3-oxo-5α-steroid, NADP+ is the acceptor and testosterone is the 3-oxo-Δ4-steroid and NADPH the reduced acceptor. Production and activity The enzyme is produced in many tissues in both males and females, in the rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5α-reductase Inhibitor
5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes of 5α-reductase encoded by the genes SRD5A1, SRD5A2, and SRD5A3. 5α-Reductases catalyze the following generalized chemical reaction: :a 3-oxo-5α-steroid + acceptor a 3-oxo-Δ4-steroid + reduced acceptor Where a 3-oxo-5α-steroid and acceptor are substrates, and a corresponding 3-oxo-Δ4-steroid and the reduced acceptor are products. An instance of this generalized reaction that 5α-reductase type 2 catalyzes is: :dihydrotestosterone + NADP+ \rightleftharpoons testosterone + NADPH + H+ where dihydrotestosterone is the 3-oxo-5α-steroid, NADP+ is the acceptor and testosterone is the 3-oxo-Δ4-steroid and NADPH the reduced acceptor. Production and activity The enzyme is produced in many tissues in both males and females, in the rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2006 Tour De France
The 2006 Tour de France was the 93rd edition of the Tour de France, one of cycling's Grand Tours. It took place between the 1st and the 23rd of July. It was won by Óscar Pereiro following the disqualification of Floyd Landis. Due to the United States Anti-Doping Agency announcing on August 24, 2012, that they had disqualified Lance Armstrong, a former teammate of Landis, from all of his results since August 1, 1998, including his seven Tour de France titles from 1999 to 2005, this is also the first Tour to have an overall winner since 1998. By terms of margin of victory the 2006 Tour was the 3rd closest of all time. The Tour began with a prologue in Strasbourg, on the French-German border, and ended on Sunday 23 July in Paris. The distance of the course (run counterclockwise around France) was . The race was the third fastest in average speed. Along the way, the cyclists passed through six different countries including France, The Netherlands (a stop at Valkenburg in Stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floyd Landis
Floyd Landis (born October 14, 1975) is an American former professional road racing cyclist. He finished first at the 2006 Tour de France, and would have been the third non-European winner in the event's history, but was disqualified after testing positive for performance-enhancing drugs. The competition was ultimately won by Óscar Pereiro. Landis was an all-around rider, with special skills in climbing, time-trialing, and descending. He turned professional in 1999 with the Mercury Cycling Team, joined the U.S. Postal Service team in 2002, and moved to the Phonak Hearing Systems team in 2005. In January 2010, a French judge issued a national arrest warrant for Landis on computer hacking charges related to the 2006 doping allegations. Until 2010, Landis maintained his innocence and mounted a defense. Although his legal team documented inconsistencies in the handling and evaluation of his urine samples, the disqualification was upheld. He was suspended from professional compe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testosterone (medication)
Testosterone (T) is a medication and naturally occurring testosterone, steroid hormone. It is used to treat male hypogonadism, gender dysphoria, and certain types of breast cancer. It may also be used to increase athletic ability in the form of doping in sport, doping. It is unclear if the use of testosterone for andropause, low levels due to aging is beneficial or harmful. Testosterone can be used as a gel or transdermal patch, patch that is applied to the skin, intramuscular injection, injection into a muscle, tablet that is Buccal administration, placed in the cheek, or tablet that is taken oral administration, by mouth. Common side effects of testosterone include acne, swelling (medical), swelling, and gynecomastia, breast enlargement in men. Serious side effects may include liver toxicity, heart disease, and behavioral changes. Women and children who are exposed may develop virilization, masculinization. It is recommended that individuals with prostate cancer not use the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mary Decker
Mary Teresa Slaney (formerly Tabb, née Decker, born August 4, 1958) is a retired American middle-distance runner. During her career, she won gold medals in the 1500 meters and 3000 meters at the 1983 World Championships, and was the world record holder in the mile, 5000 meters and 10,000 meters. In total, she set 17 official and unofficial world records, including being the first woman in history to break 4:20 for the mile. She also set 36 US national records at distances ranging from 800 meters to 10,000 meters, and has held the US record in the mile, 2000 meters and 3000 meters since the early 1980s, while her 1500 meters record stood for 32 years. In 2003, she was inducted into the National Track and Field Hall of Fame.Mary Slaney (Decker) at USA Track & Field Hall of Fame Early life ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Androstanes
An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands. Androgens increase in both males and females during puberty. The major androgen in males is testosterone. Dihydrotestosterone (DHT) and androstenedione are of equal importance in male development. DHT ''in utero'' causes differentiation of the penis, scrotum and prostate. In adulthood, DHT contributes to balding, prostate growth, and sebaceous gland activity. Although androgens are commonly thought of only as male sex hormones, females also have them, but at lower levels: they function in libido and sexual arousal. Also, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
17α-Estradiol
17α-Estradiol (also known as 17α-E2, 17-epiestradiol, alfatradiol, or estra-1,3,5(10)-triene-3,17α-diol) is a minor and weak endogenous steroidal estrogen that is related to 17β-estradiol (better known simply as estradiol). It is the C17 epimer of estradiol. It has approximately 100-fold lower estrogenic potency than 17β-estradiol. The compound shows preferential affinity for the ERα over the ERβ. Although 17α-estradiol is far weaker than 17β-estradiol as an agonist of the nuclear estrogen receptors, it has been found to bind to and activate the brain-expressed ER-X with a greater potency than that of 17β-estradiol, suggesting that it may be the predominant endogenous ligand for the receptor. Aging Supplementation with 17α-Estradiol increases the median lifespan of male mice by 19%, while not affecting female lifespan. This treatment does not lead to feminization of male mice. 17α-Estradiol furthermore alleviates age-related metabolic and inflammatory dysfunct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ESPN
ESPN (originally an initialism for Entertainment and Sports Programming Network) is an American international basic cable sports channel owned by ESPN Inc., owned jointly by The Walt Disney Company (80%) and Hearst Communications (20%). The company was founded in 1979 by Bill Rasmussen along with his son Scott Rasmussen and Ed Eagan. ESPN broadcasts primarily from studio facilities located in Bristol, Connecticut. The network also operates offices and auxiliary studios in Miami, New York City, Las Vegas, Seattle, Charlotte, Washington, D.C., and Los Angeles. James Pitaro currently serves as chairman of ESPN, a position he has held since March 5, 2018, following the resignation of John Skipper on December 18, 2017. While ESPN is one of the most successful sports networks, there has been criticism of ESPN. This includes accusations of biased coverage, conflict of interest, and controversies with individual broadcasters and analysts. , ESPN reaches approximately 76 million te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotope-ratio Mass Spectrometry
Isotope-ratio mass spectrometry (IRMS) is a specialization of mass spectrometry, in which mass spectrometric methods are used to measure the relative abundance of isotopes in a given sample. This technique has two different applications in the earth and environmental sciences. The analysis of ' stable isotopes' is normally concerned with measuring isotopic variations arising from mass-dependent isotopic fractionation in natural systems. On the other hand, radiogenic isotope analysis involves measuring the abundances of decay-products of natural radioactivity, and is used in most long-lived radiometric dating methods. Introduction The isotope-ratio mass spectrometer (IRMS) allows the precise measurement of mixtures of naturally occurring isotopes. Most instruments used for precise determination of isotope ratios are of the magnetic sector type. This type of analyzer is superior to the quadrupole type in this field of research for two reasons. First, it can be set up for multiple-c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
